The invention relates to a machine knitting needle which is intended, in particular, for high-speed circular knitting machines, however, basically also for all other types of knitting machines or even for warp knitting machines.
Machine knitting needles have been known, for example, from documents U.S. Pat. No. 1,629,725 or also from DE 29 07 569 B1. Increasingly, greater demands are made on such needles in view of higher knitting speeds. During the knitting operation, the needle is moved back and forth in longitudinal direction. In so doing, half stitches picked up by the hook of the needle slide onto the shaft, in which case they move a latch provided on the machine knitting needle into back position, for example. This motion is supported by the inherent inertia of the latch. Therefore, the latch moves back and forth between the closed position and the back position, in which case it alternately abuts against the hook and the shaft. In order to illustrate this, FIG. 5 shows such a needle P1. As a result of its acceleration due to the half stitch, the latch P2 is accelerated when the half stitch slides over the curved section P3 of the maximum jaw height. Consequently, the latch is accelerated by the half stitch in the relatively large angle range ε, thus resulting in a high impact speed. As the knitting speed increases, the impact of the latch, in particular in back position, represents a problem regarding in view of the durability of a machine knitting needle. Thus, it must be ensured that no inadmissible wear of the knitting needle and, in particular, no breakage of the latch or of the needle body occur over the duration of use of the machine knitting needle.
In order to remedy this, it has already been attempted to dampen the impact of the latch when it pivots into the back position and abuts against the shaft. Regarding this, document DE 27 14 607 C3 discloses a special embodiment of the needle slit that is limited by more or less elastically configured shaft jaws. The elastic shaft jaws catch the latch in an elastic manner and thus dampen the impact.
However, it is also necessary to consider aspects that relate to the thread. For example, it may happen that the thread is partially cut on the latch. In conjunction with this, the cited DE 29 07 569 B1 provides the latch with a throat and configures the ascent from the hook to the breast of the needle with a relatively steep slope angle β. It is true, that this is more gentle on the thread but it leads to compromises with respect to the operating speed. In particular, as explained above, this results in a high latch impact speed of the latch at the shaft, when the latch impacts in back position.
The objective is to use latch-type needles that increasingly higher operating speeds.
With this in mind, it is the object of the invention to improve the machine knitting needles.